You want microservices, but do you need them?

The definitional size I've read and heard is that you team could (with the benefit of hindsight) be able to reimplement a microservice in 2 weeks. That sounds fairly extreme but a month seems within reason to me.

The other key difference between microservices and other architectures is that each microservice should do its primary function (temporarily) without hard dependencies, which basically means having a copy of the data that's needed. Service Oriented Architecture doesn't have this as one of its properties which is why I think of it as a mildly distributed monolith. "Distributed monolith" is the worst thing you could call a set of microservices--all the pain without the gains.

I don't want or need microservices. What I want is for people to stop putting TCP roundtrips in between what would otherwise be simple function calls in a sane universe. I don't want to have to take a graduate-level course on the CAP theorem to clock in and work on whatever "Uber for dogs" nonsense is paying my rent. You almost certainly don't have a scaling problem that necessitates a distributed system, I guarantee it. I have had an average career, and every single time someone shoved a Kubernetes-shaped peg into a server-shaped hole, it's been a shitshow. These systems are slow, expensive, difficult to reason about, and largely unnecessary for most people who handle a few hundred or thoudsand connections per second (on average. Don't @ me about bursty traffic, I understand how it works).

And in a few days, we're going to get a long thread about how software is slow and broken and terrible, and nobody will connect the dots. Software sucks because the way we build it sucks. I've had the distinct privilege of helping another team support their Kubernetes monstrosity, which shat the bed around double-digit requests per second, and it was a comedy of errors. What should've otherwise just been some Rails or Django application with HTML templating and a database was three or four different Kubernetes pods, using gRPC to poorly and unnecessarily communicate with each other. It went down all. The. Time. And it was a direct result of the unnecessary complexity of Kubernetes and the associated pageantry.

I would also like to remind everyone that Kubernetes isn't doing anything your operating system can't do, only better. Networking? Your OS does that. Scheduling? Your OS does that. Resource allocation and sandboxing? If your OS is decent, it can absolutely do that. Access control? Yup.

I can confidently say that 95% of the time, you don't need Kubernetes. For the other 5%, really look deep into your heart and ask yourself if you actually have the engineering problems that distributed systems solve (and if you're okay with the other problems distributed systems cause). I've had five or six jobs now that shoehorned Kubernetes into things, and I can confidently say that the juice ain't worth the squeeze.

Heh, split databases is the thing I think is most problematic and the first thing I would eliminate in most microservices architectures. A huge fraction of the problems of microservices come from trying to split the data model along team structure / service domain rather than the true application / underlying business domain. It doesn't mean you shouldn't have multiple database, just the concept of splitting them arbitrarily along service lines is a huge cause of friction / impedance mismatch / overhead.

I actually like close to a full microservice architecture model, once you allow them all to share the database (possibly through a shared API layer).

It has other advantages.

Operationally, it is very nice to be able to update one discrete function on its own in a patch cycle. You can try to persuade yourself you will pull it off with a modular monolith but the physical isolation of separate services provides guarantees that no amount of testing / review / good intentions can.

However, it's equally an argument for SOA as it is for microservices.